Posts tagged Water Quality
2018 Cooperative Lakes Monitoring Program  

The 2018 Cooperative Lakes Monitoring Program (CLMP) report was issued and can be reviewed by clicking the button at the bottom of this post.  The results of the report cover the transparency, Phosphorus content, and Trophic Status.  This year’s program also included an Exotic Aquatic Plant Watch.

Transparency is measured using a Secchi disk, a very simple but effective method to determine water clarity. Phosphorus concentration is determined by taking water samples and sending them to a lab for processing. Phosphorus is one of the critical nutrients for algae growth and is important to monitor.  The Trophic Status Index (TSI) is a single figure used to assess the nutrient enrichment of a lake.  

The average Secchi depth is 16.7, which is the same as previous years.  The summer phosphorus sample is 6 parts per billion, which is lower than previous years. The TSI is also lower than previous years at 33, which is influenced by the Secchi depth and the phosphorus content.

The departure in phosphorus and TSI from previous years does not reveal any trends. It is normal for values to fluctuate from year to year. The purpose of the CLMP is to monitor lakes to prompt action when a clear trend in either direction appears. The next step would be to identify the mechanism causing the trend and come up with a solution.

The Exotic Aquatic Plant Watch surveyed multiple locations around the lake to identify and document the extent of invasive aquatic species. As of August 24th 2018, Gratiot Lake does not contain any of the invasive aquatic plant species on the watch list. For a complete list please review the report below.

2017 Cooperative Lakes Monitoring Program Report

Gratiot Lake Conservancy (GLC), in conjunction with some lake locals, collects data points annually to contribute to the Cooperative Lakes Monitoring Program (MiCorps). GLC has been providing data since 1999 to the program and is excited to continue to in the future.

MiCorps is a network of volunteer water quality monitoring programs in Michigan. It was created through Michigan Executive Order #2003-15 to assist the Department of Environmental Quality (DEQ) in collecting and sharing water quality data for use in water resources management and protection programs. To learn more about them click here: About MiCorps .

The 2017 report indicates Gratiot Lake is a 36 on the Trophic Scale Index, a metric used to evaluate the productivity, quality, and condition of a lake. The 36 places Gratiot Lake between an Oligatrophic Lake (think a barren, not very productive lake) and a Mesotrphic lake (medium amount of aquatic life and relatively productive). Given the size of Gratiot Lake, this ranking makes sense and is a good indicator of a healthy lake.

It is important to continue these measurements in order to monitor the condition and quality of the lake. If Gratiot Lake starts moving to a higher or lower number (scale is 0-100), it could indicate a potential problem or threat to the lake’s ecosystem and food web.

Dorothy Jamison taking Secchi Reading at Gratiot Lake in 2014

Dorothy Jamison taking Secchi Reading at Gratiot Lake in 2014